1. Field of the Invention
This invention relates to a system and method for wastewater treatment, and in particular to a system and method for treating low concentration wastewater streams.
2. Description of Related Art
Effective handling of domestic sewage and industrial wastewater is an extremely important aspect of increasing the quality of life and conservation of clean water. The problems associated with simply discharging wastewater in water sources such as rivers, lakes and oceans, the standard practice up until about a half century ago, are apparent—the biological and chemical wastes create hazards to all life forms including the spread of infectious diseases and exposure to carcinogenic chemicals. Therefore, wastewater treatment processes have evolved into systems ranging from the ubiquitous municipal wastewater treatment facilities, where sanitary wastewater from domestic populations is cleaned, to specialized industrial wastewater treatment processes, where specific pollutants in wastewater from various industrial applications must be addressed.
Wastewater treatment facilities typically use multiple treatment stages including preliminary treatment, secondary treatment and tertiary treatment. Biological oxidation is a well known secondary treatment step used to remove the majority of the wastewater contaminants. Commonly, effluent from biological oxidation and/or other secondary treatment processes still contains levels of contaminants that requires further treatment such as tertiary treatment for their removal.
Biologically refractory and biologically inhibitory organic and inorganic compounds are present in certain industrial and sanitary wastewater streams to be treated. Various attempts have been made to address treatment of such biologically refractory and biologically inhibitory compounds. Certain types of known treatment include use of powdered activated carbon to adsorb and subsequently remove biologically refractory and biologically inhibitory organic compounds.
One portion of certain wastewater treatment processes that is operationally cost-intensive involves the removal of relatively low concentrations of contaminants from wastewater that has been treated by aeration or other secondary processes. While various systems have been employed for tertiary treatment, such as adsorption and filters, a need exists for more efficient and lower cost tertiary treatment without the limitations and disadvantages associated with conventional processes.